Much of Miami's housing is older than people expect. Mid-century houses in Little Havana, Shenandoah, Coral Gables and Hialeah often have galvanized supply pipes and cast iron drains near the end of their life.
Miami Beach buildings share vertical drain stacks, so one leak can cross several units. At the far edge of the county, septic systems replace city sewer.
The water table is high, yards stay wet, and in the fall the king tides push seawater up into low streets and storm drains. Summer downpours do the same. Water heaters here fail mostly from age, not cold, so many calls come without warning.